Process for the continuous production of laminated wood of the parquet type

ABSTRACT

The invention relates to a process for the step by step pressing of material which is fed continuously, particularly wood laminate such as laminated parquet, and the like, in which the pressing is carried out by means of a press which can move to and fro in the feed direction of the material and supported by rollers or wheels. The press carries out the pressing and the heating of the laminate in order to harden the glue while moving in the feed direction of the material and which is open during the return movement, and the press is pushed forward by the material sheet itself and one thereby achieves a desired mutual compression of the lamellae in the horizontal direction.

June 1 L. T. OLSEN PROCESS FOR THE CONTINUOUS PRODUCTION OF LAMINATEDWOOD OF THE PARQUET TYPE Flled March 26. 1969 3 Sheets-Sheet l Q4//r AFIG. 1

INVENTOR. Lf/ ruaaunm man BY lwwm June 20, 1972 L. T. OLSEN PROCESS FORTHE CONTINUOUS PRODUCTION OF LAMINATED WOOD OF THE PARQUET TYPE 3Sheets-Sheet 2 Filed March 26, 1969 NH A A 535 INVENTOR. LEIF 1' OR #91.D 01.55.42

hmwwzm ATTORME/S June 20, 1972 T. OLSEN 3,671,353

PROCESS FOR THE CONTINUOUS PRODUCTION OF LAMINATED WOOD OF THE PARQUETTYPE Filed March 26, 1969 3 Sheets-Sheet 5 FIG. 4

INVENTOR. LEI TII RVH D 0 EA) ma/w) fi TTORMSIS United States Patent3,671,353 PROCESS FOR THE CONTINUOUS PRODUCTION OF LAMINATED WOOD OF THEPARQUET TYPE Leif T. Olsen, Boen, Norway, assignor to Boen Bruk,Kristiansand 8., Norway Filed Mar. 26, 1969, Ser. No. 810,589 Claimspriority, application Norway, Apr. 1, 1968, 1,252; June 27, 1968, 2,554;Feb. 11, 1969, 526 Int. Cl. B32b 31/10, 31/20 US. Cl. 156-302 4 ClaimsABSTRACT OF THE DISCLOSURE The invention relates to a process for thestep by step pressing of material which is fed continuously,particularly wood laminate such as laminated parquet, and the like, inwhich the pressing is carried out by means of a press which can move toand fro in the feed direction of the material and supported by rollersor wheels. The press carries out the pressing and the heating of thelaminate in order to harden the glue while moving in the feed directionof the material and which is open during the return movement, and thepress is pushed forward by the material sheet itself and one therebyachieves a desired mutual compression of the lamellae in the horizontaldirection.

This invention relates to a process for the continuous production ofwood laminate, especially laminated parquet, consisting of lamellae inthe form of narrow boards or laths, laid cross-wise and glued andpressed together by means of a press which can move to and fro. Furtherthe invention relates to a device for carrying out the process.

Parquet of this type usually has an underside of thin, relatively longand narrow lamellae oriented in the lon gitudinal direction of theparquet strips. Upon this layer, there is positioned an intermediatelayer of thin lamellae which lie across the first layer and finally ontop of this layer lies the wearing surface, or visible surface, itselfwhich consists of long lamellae of a more noble type of wood than theother two layers, and which is oriented in the same direction as thefirst layer. Hitherto parquet of this type has been produced in astandard stationary press, for example a multi-storey press in which thelamellae in the various layers are laid on top of one another by hand.This is a time-consuming method and furthermore demands very expensivepress equipment as it is necessary to have several presses in order thatthe work may proceed continuously. Naturally, it has long been a wish inthe parquet industry to produce laminated parquet in the form of acontinuously manufactured sheet. Such a method of production is known inthe plywood industry, but hitherto it has not been successful inconnection with the production of laminates of the above mentioned type.For the method in question of producing plywood, a gluing press is usedwhich can be moved to and fro. The press is accelerated from its initialposition to a synchronous speed with the lamella sheet, and is presseddown onto the sheet when this synchronous speed has been reached and isthereupon driven synchronously with the lamella sheet an expedientdistance, after which the pressure is released and the press is returnedto its initial position. During the distance the press follows the sheetof plywood, the sheet is supplied with heat from the press, in such away that the glue hardens.

Attempts have been made to apply this method to the production oflaminated parquet, but in practice it has proved impossible to move thepress in exact synchronization with the speed of the lamella sheet as itis fed 3,671,353 Patented June 20, 1972 ice forward, and this is anabsolute condition for the success of this method when applied tolaminated parquet. If the press moves too fast, a stretching of thelamella sheet in its longitudinal direction will result and theindividual lamellae will slide away from one another with the resultthat cracks will appear across the visible layer. If the press moves tooslowly, the lamella sheet will pile up behind press as, in such anevent, the lamella sheet moves faster than the press with inevitabledestruction of the sheet. Another problem which arises in the productionof a continuous sheet of laminated parquet is that of pressing thelamellae together in the longitudinal direction of the sheet. Thisproblem does not apply in the production of plywood as the two outercovering layers at least consist of very large whole sheets of material.A significant problem in the continuous production of laminated parquetis that the middle, transverse lamella layer consists of short,preferably not exceeding 0.5 metre long, small and thin lamellae. Thelength of these lamellae is limited by the fact that the breadth of thepress equipment and the conveyor belt must be kept to a reasonable size.As the material in these thin, short lamellae is usually of very poorquality, in order to keep the price as low as possible, these lamellaewill often be broken into two or more pieces when glue is applied tothem and they are laid into position in the layer.

The present invention aims at furnishing a method and device for thecontinuous production of wood laminate of the laminated parquet type, inwhich the production is trouble-free and entirely continuous without theabove mentioned disadvantages arising.

According to the invention, this is achieved by means of a process inwhich the pressing is carried out by means of a press which can move toand fro in the feed direction of the material, which pres's carries outthe pressing and the heating in order to harden the glue during itsmovement in the feed direction of the material and which is open duringits return movement, and the characteristic feature is primarily thatthe press is moved forward by the sheet of material itself and that adesired compression of the lamellae across the material sheet is thusachieved.

The above mentioned desired compression of the lamella sheet, is aresult of the fact that it is the lamella sheet itself, which is fedforward continuously, which pushes the press from one position toanother under the influence of a certain rolling friction between therollers of the press and the track. In order to maintain completecontrol over the feed resistance, a variable mechanical resistance maybe included which works against the forward feed of the press or thelamella sheet. A mechanical resistance of this type can, for example,consist of friction surfaces which, with a given force, are pressedagainst the ready glued lamella sheet behind the press.

The lamella sheet arrives at the pressing region ready assembled, gluedand partly compressed. When the press is in its most advanced positionin the feed direction of the sheet, there will be a section of readyglued and packed lamella sheet behind the press which is supported onlyby a conveyor belt or a roller conveyor underneath, whilst there isnothing which holds the sheet together from above. In practice, it hasproved that the resistance working against the forward feed of the pressand the lamella sheet can vary within certain limits. This may be due tothe presence of wood particles, dust and the like on the track on whichthe press runs, which increase the rolling friction, or some glue or thelike may adhere to the brake blocks of the above mentioned mechanicalfriction device with the result that the device during certain periodsoffers more resistance than usual. As the aforementioned section oflamella sheet approaching the press has not been properly glued inasmuchas the glue has not hardened, this increased resistance can easilyresult in the entire sheet, or part of the upper layer, bulging upwards,interrupting production. This means reduced production and thus highercosts per square meter of laminate produced.

Many attempts have been made to solve this problem, but it has provedimpossible to solve with holding-down devices known hitherto as thesection of lamella sheet which has to be held down against theunder-surface, varies in length all according to the position of thepress. At one moment of time, there will be no free area whilst at thenext moment when the press is in its fully advanced position, the freearea is a couple of metres long.

This particular problem is solved, according to the invention, by havingthe press move in the feed direction of the material sheet, weightsbeing continuously applied, distributed along the length of sheet whichfollows the press, which weights are removed when the press is returned.

The problem of pressing together the above mentioned transverse narrowand thin lamellae of comparatively poor quality to form a close surfaceis solved, according to the invention, by the first layer of lamellaebeing fed close against one another on a continuously running conveyorbelt with its longitudinal axis in the direction of movement of thebelt, and by there thereafter being fed in a second layer of lamellaeacross the first layer and further layer upon layer up to the requiredthickness of lamella layer, in that those lamella layers which lie withtheir axes across the direction of transportation, are coated with gluebefore they are applied to the under-lying layer, and in that theselayers are pressed together by their own weight before the applicationof glue, in that the lamellae in this layer are fed in a continuoussequence into the gluing device along a smooth inclined plane.

The above mentioned and further features of the invention will beapparent from the following and will be described in more detail withreference to the drawings which in diagram form show a device for thecontinuous production of laminated parquet.

FIG. 1 shows the gluing press together with a part of the row oflamellae in the region near the gluing press.

FIG. 2 shows a plant for the production of laminated parquet seen fromthe side.

FIG. 3 shows the lamella sheet seen from above and FIG. 4 like FIG. 2,shows the plant seen from the side in a somewhat modified embodimentcompared with FIG. 2.

The various layers in the laminate 1 are prepared in an earlier stage inthe production line, not shown in the drawing, and are fed onto aconveyor belt 2 which runs continuously in the direction of the arrow 3.This belt 2 should have a surface with a high coefficient of frictionand, for example, consist of rubber. On the belt 2, the first layer 4 islaid consisting of long, thin and relatively narrow lamellae of cheapquality. These lamellae in layer 4 are oriented with their longitudinalaxis in the transportation direction 3 of the conveyor belt 2. Onto thislayer, a second layer 5 is fed consisting of elongated, thin and narrowlamellae which are posed across the direction of transportation 3. Theselamellae 5 are first fed by means of a conveyor belt 6 or the like to aninclined plane 7 and slide down along this by their own weight and areguided in through a gluing device 8 which applies adhesive to both sidesof this layer 5. The inclined plane 7 is so designed that the lamellaecompress together to form a layer by their own weight with sufficientforce to press the individual lamellae close together.

On top of layer 5 a new layer 9 of, for example, hardwood is laid whichis to form the visible side of the final product. This layer consists ofrelatively thin parquet strips accurately worked on all sides. On top oflayer 9, a further layer 10 is laid which is identical with layer 5 andwhich is disposed in the same manner. Also this layer is fed by means ofa transport device 11 to an inclined plane 12 and down onto layer 9through a gluing device 13. Layer 10 is pressed together by gravity inthe same way as layer 5. Onto layer 10 there is finally laid a layer 14which is identical with layer 4 and positioned in the same manner. Thelamella sheet 1 is then complete, but the glue has not hardened, norhave the various lamellae been sulficiently compresed together. Themiddle layer 9 of hardwood has, however, been pressed together in thelongitudinal direction by means of a device 15 which can consist of adriven roller having a friction surface or, as shown in FIG. 4, a spikedroller which rotates in the transportation direction with a somewhathigher speed than the conveyor belt 2.

After the lamella sheet 1 has been fully compiled, it is fed into thepressing region of the press 16 which moves to and fro (in theembodiment as shown in FIGS. 1 and 2). This conveyor belt does not haveits own drive, but is driven by the lamella sheet itself. Instead of theconveyor belt 17, the lamella sheet 1, in the region between the pressand the point where it leaves the conveyor belt, can be supported by aroller belt 18 such as shown in FIG. 4. This roller belt 18 is fixed toa point in the machine stand near the output end of the conveyor beltand runs over a roller 19 fixed to the press, is bent downwards and runsover a second roller 20 which is also fixed to the press 16. After this,the roller belt 18 is bent back into the horizontal position and isanchored in the machine stand. In this manner, when the press 16 movesto the right in FIG. 4, a roller belt will be laid out under the lamellasheet 1 and the belt will be removed again when the press moves to theleft.

The press is brought to its initial position, as shown with the dashedand dotted line in FIG. 2,1by means of an expedient device, for examplea ram 21. At this point, the press is brought to bear against thelamella sheet and is driven in the direction of transportation 3 to theleft in the figure, by the lamella sheet itself. During the movementfrom the position which is shown by the dashed and dotted line to theposition which is shown with the full line in FIG. 2, the glue in thelamella sheet is subjected to considerable heat, for example by means ofhigh frequency heating, the various layers in the laminate sheet arepressed forcefully together, and the glue hardens. The lamella sheet isthus ready glued and hardened when it leaves the press 16.

The lamella sheet 1, which may have a width of, for example, 0.5 metre,is divided into suitable lengths of, for example, 3 metres. This 3 metrelong lamella package is then divided longitudinally into, for example,three smaller pieces. These three pieces are then divided along ahorizontal plane in the middle of the hardwood layer 9. In order thatthe parquet strips prepared in this manner will be easy to lay, they areprovided with tongue and groove on their long sdes and ends. In order toavoid using the expensive hardwood for that piece where the tongue is tobe made, thin, narrow wooden laths of a cheaper type of wood areinserted into the hardwood layer 9. Similarly, in the middle layers 5and 10, somewhat broader lamellae 19 may be inserted at those placeswhere the lamella sheet is to be sawn lengthwise. This is done in orderthat the fibres will run longitudinally in all those layers which attheir ends are to be formed into tongues and grooves.

In order to achieve an even pressure against the press, and also acompression of the hardwood lamellae in the longitudinal axis of theconveyor belt, there may in addition to the conveyor belt 2, be includeda further conveyor belt 22 which is positioned nearer the press 16. Thefirst belt 2 is driven at a somewhat higher speed than belt 22.

Before the lamella sheet is pressed and heated by the press 16 in orderto harden the glue, the individual lamellae must be pressed togetheracross the sheet similar to the lengthwise compression described above.This is achieved quite simply by means of pressing devices (not shown inthe drawing), which are guided in towards the sheet from both sides andwhich press together those lamellae which are oriented along the sheet.With such a compression operation, however, there arises the danger ofthe lamellae being pressed out of position. This is eliminated,according to the invention, in that the press in its initial position isfirst brought together over the material sheet with a small clearancedown to the sheet, and in that the material sheet with the press in thisposition, is pressed together by the pressing devices operating from thesides and in that the press is then brought into full engagement againstthe material sheet.

As already described, the press 16 is pushed forward by the materialsheet itself with the result that one thus achieves a desiredcompression of the lamellae. In order to hold the individual lamellae inthe lamella sheet in their proper places there is, at the output end ofthe conveyor belt 22, on the upper-side of the lamella sheet disposed apress-down roller 23. However, as the press 16 moves away from thisroller, there will be a considerable section of the lamella sheet 1lying open without any support from above. In order to prevent thelamella sheet, in the event of varying resistance against the movementof the press 16, bulging upwards and cracking, weights 24 are arrangedabove the sheet 1, these weights being linked together to form a chainwhich, near the roller 23, is fixed to the machine stand and which runsover two deflecting rollers 25 and 26 on the press 16. The other end ofthe chain of weights 24 is fixed to the machine stand above the press16. In order to achieve a controlled and adequate resistance against theforward feed of the lamellae sheet 1, and thus a sufiicient compressionof the lamellae, behind the press 16 there is disposed a friction device27 which may consist of a fixed shoe and a sprung shoe which both pressagainst the lamella sheet from the underside and overside respectively.

Having described my invention, 1 claim:

1. A process for pressing wood laminate material for forming laminatedparquet comprising the steps of forming a multi-layer laminate oflamellae and applying glue to the lamellae, supporting the laminate inthe horizontal position, continuously feeding the laminate along ahorizontal feed path, applying a pressing and heating action to aspecific length of the laminate for effecting compression of thelaminate and hardening of the glue, wherein the improvement comprisesapplying the pressing and heating action in the path of the continuousfeeding of the laminate, and maintaining the pressing and heating actionon the specific length of the laminate for a predetermined length oftravel as it is continuously fed solely by the feeding action applied tothe laminate upstream from the location of the pressing andlheatingaction, and removing the pressing and heating action from the laminateafter the predetermined length of travel for pressing and heating hasbeen accomplished.

2. A process, as set forth in claim 1, wherein the step of feeding thelaminate comprises continuously moving a horizontal support surface inthe feed direction, and the step of forming the multi-layer laminatecomprises continuously depositing a first layer of lamellae extending inthe feed direction on the support surface, continuously depositing asecond layer of lamellae on the first layer with the lamellae of thesecond layer extending transversely across the feed direction of thelaminate, applying adhesive to the surfaces of the lamellae forming thesecond layer, repeating the application of first and second layers withthe application of the adhesive only to the surfaces of the secondlayers until the desired number of layers of the laminate are formed,and supplying the lamellae forming the second layers from a positionabove the support surface down an inclined surface with the individuallamellae in side-by-side contacting relationship so that the weight ofthe lamellae on the inclined surface presses the lamellae of the secondlayer together prior to the application of the adhesive.

3. A process, as set forth in claim 2, comprising the step of depositingan intermediate first layer of lamellae formed of a hard wood on asecond layer of lamellae for forming the finish parquet surface, andsplitting the laminate after the completion of the pressing and heatingaction along a plane extending through the intermediate first layerformed of hard wood to provide two sheets having a finish parquetsurface.

4. A process, as set forth in claim 3, comprising the step of insertingtransversely spaced longitudinally extending lamellae in theintermediate layer of hard wood with the inserted lamellae being of alower grade of wood than the hard wood forming the intermediate layer,and sawing the laminate longitudinally after the completion of thepressing and heating step in the longitudinal direction through theinserted longitudinally extending lamellae.

References Cited UNITED STATES PATENTS 3,177,568 4/1965 Schweiker156-561 3,389,038 6/1968 Robison 156-503 3,255,067 6/1966 Sontheim eta1. 156-522 3,272,680 9 /1966 Paasche 186-160 BENJAMIN A. BORCHELT,Primary Examiner J. V. DORAMUS, Assistant Examiner US. Cl. X.R. 156-656,522

